Field of the Invention
The present invention relates to a switching regulator.
Background Art
COT (Constant On Time) control has been known as one of control methods of a switching regulator.
FIG. 3 is a circuit diagram of a related art COT-controlled switching regulator.
The switching regulator 300 causes an R-S flip-flop 13 to output a signal controlling a switching element in accordance with a signal outputted from an error comparator 10 which compares a feedback voltage VFB based on an output voltage VOUT and a reference voltage VREF, and a signal outputted from an on-time control circuit 31. The on-time control circuit 31 is a circuit essential in the COT control.
FIG. 4 is a circuit diagram of a related art on-time control circuit.
The on-time control circuit 31 charges a capacitor 32 with a current proportional to an input power supply voltage VIN, which is made to flow by a current source 33 and causes a comparator 35 driven by a current made to flow by a current source 34 to compare the voltage of the capacitor 32 with the output voltage VOUT to determine an on-time. Thus, the on-time control circuit 31 determines an on-time inversely proportional to the input power supply voltage VIN and proportional to the output voltage VOUT (refer to, for example, Patent Document 1).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2015-188300
However, a reduction in power consumption of an analog circuit block in addition to a reduction in the on resistance of a switching element has been an urgent need for the recent battery-driven portable device and wearable device for which lower power consumption and an improvement in efficiency are required.